The present invention relates to blast furnace equipment, and more particularly to charging devices.
For example, there is known in the art a blast furnace charging device which is a combination of a McKee distributor and two Parry bell-and-hopper arrangements mounted one above the other and fitted with bell rods. Upon dumping each skipload the upper hopper is turned through a preset angle thereby diminishing to a certain extent but not eliminating completely the negative influence of distributing the charge in heaps peculiar to this type of charging apparatus. As a result, both the chemical and heat energy of reducing gases is under utilized. Another disadvantage of this prior-art charging device lies in that it fails to provide reliable control over radial distribution of charge at a furnace top.
There is also known in the art a charging device comprising a bottom bell with a fixed hopper and a top bell with a rotary hopper. Mounted above the top bell is a sealing valve-cover (see e.g., French Pat. No. 1240287).
The valve of the patent referred to above has a soft packing between its tapered surface and the top portion of the rotary hopper, and a labyrinth packing around the bell rod. When loading a belt-fed charge, the cover is raised. Upon feeding a full batch of the charge, the cover is closed and the charge is lowered into a blast furnace. Said charging device is characterized by a sophisticated design and fails to provide reliable functioning of the blast furnace at a high top gas pressure.
Known as well in the art is a charge distributor (see, e.g., Inventor's Certificate of the USSR No. 132652) comprising two large Parry bells with fixed hoppers. To enable uniform peripheral distribution of the charge at a furnace top arranged above the upper hopper is a rotary hopper, whose internal surface is fitted with inclined blades, said rotary hopper being mounted beneath a movable hopper driven along horizontal guideways so that its outlet can be disposed in a corresponding place of the rotary hopper. Such a design enables a requisite irregular charging to be achieved for various sectors of the furnace top.
However, this charging device is characterized by extremely severe operating conditions of its equipment, a drive and support rollers of the bladed rotary hopper in particular, whereby it is impossible to attain a speed above 18 rpm. Yet, even at this speed there arise undue efforts as the charge is accumulated in heaps up to ten tons in weight on one side of the rotary hopper. As a result, the rollers and races adapted to carry such heavy heaps of charge fail after one or two months of operation, with the rotary hopper being incapable of attaining such angular speed at which the requisite uniform peripheral distribution of the charge is ensured.
The Inventor's Certificate of the USSR No. 105602 describes a charging device with a charge distributor, said device comprising two bells with fixed hoppers and rods, above which a receiving hopper is arranged. Mounted intermediate of said receiving hopper and the top bell is a rotary hopper with two sloping surfaces and two outlets. Upon leaving the receiving hopper the charge is admitted onto the rotary hopper wherefrom it drops through the two outlets to be uniformly spread over on the top bell. However, in the course of functioning of said charging device there may take place a hanging of the charge in the rotary hopper, which may be responsible for the blast furnace banking.
Moreover, the provision of two outlets in the hopper makes it impossible to concentrate the charge, if necessary, in a particular preset sector at the furnace top.
Another prior-art charging device (see, e.g., Japanese Pat. No. 7809) comprises two bells with fixed hoppers. Arranged above the upper hopper are two plate valves with a bunker being located therebelow, the bunker outlet being narrowed and its walls formed with guide blades. The valves are fitted with a soft rubber packing. With the valves being open, the plates are drawn out of the flow of a dropping charge to be thereby saved from wearing which may be caused by the moving stock. A small bell rod is lined with the aid of guard rings and has a packing in a gas seal. However, a considerable height of this device has turned out to be a serious problem. Therefore, the same firm has proposed another embodiment of a bell-and-hopper arrangement (see, Japanese Pat. No. 7808), with a bottom bell having two rods located eccentrically to the longitudinal axis of the furnace. The disadvantage of the charging devices with the plate valves resides in that they require a thorough sizing of the charge to preclude the ingress of large lumps. The use of unsorted charge leads to a strongly pronounced peripheral segregation, a feature diminishing materially the economic effect of the blast furnace process.
The disadvantage inherent in the above outlined charging devices consists in that they fail to provide for efficient control of the radial charge distribution at the furnace top. To enable said efficient control of the radial distribution of charge at the furnace top, there have been developed manipulators with movable plates, disclosed in GFR Pat. Nos. 1221255, 1250463, 1206454, 1229565, 1230051 and 1231734. As can be seen from the disclosure of the above patents, mounted round the entire circumference of the furnace top are driven plates capable of being transferred radially at the furnace top, thereby varying its diameter. This affords the possibility of changing the arrangement of a charge cone top and radial burden distribution. The disadvantage of said device lies in its large overall dimensions, which complicates the construction of the furnace top, and its low reliability in service. This equipment operates under severe conditions, specifically by a high temperature, dust-laden atmosphere and high gas pressure.
Also known in the art is a charging device comprising bunkers with upper and lower gate valves and adapted for efficient control of both radial and peripheral charge distribution at a furnace top. Arranged beneath the bunkers is a driven pan (see, e.g., GFR Pat. No. 126614 and Czechoslovakian Pat. No. 88154). As the charge is being poured down, the pan can be either rotated or placed in any assigned sector, this feature providing for the requisite peripheral and radial distribution of the charge. The disadvantage of said device resides in its low functional reliability. In the case a rotary gear fails, the charging of a blast furnace shall cease, insofar as the fines, contained in the charge, will accumulate in one sector of the furnace top. As for using unsorted charge, it does not ensure the requisite regular peripheral dispensing of the charge.
There is likewise known a blast furnace charging device comprising a large and a small bell with hoppers and rods. Mounted above the bell is a receiving hopper with an appliance for adjusting its outlet area (see, e.g., Inventor's Certificate of the USSR No. 374374). In terms of its geometry the appliance is shaped as plates fitted with counterweights and articulated around the outlet. As the charge passes through the outlet, its flow is constricted under the action of said plates, the charge being therefore concentrated around the rod. This feature contributes to an averaged peripheral distribution of the charge. The disadvantage of this charging device is apparent when the charge is traveling the plates may jam, being registered in that position and distorting therefore the preset configuration of the outlet. Moreover, the device fails to provide charge accumulation in the assigned sector of a furnace top. It is also not able to adjust radial charge distribution at the furnace top.
A great number of patents granted for various constructions of blast furnace charging devices are indicative of extreme importance of the problem, which has been and is attracting the attention and efforts of a considerable number of those skilled in the art and engaged in providing substantial improvements in the prior-art developments.
The main object of the present invention is the provision of a blast furnace charging device which would be simpler in terms of its design and more reliable and durable in service than the prior-art devices of similar application.
Another no less important object of this invention is to provide better charge distributing at a furnace top in terms of both more regular peripheral distribution and charging a batch into a preset section at the furnace top.
Still another important object of the invention is to decrease the overall dimensions of a large bell and its hopper and to reduce gas and dust release through the furnace charging device.
These and other objects are achieved by providing a blast furnace charging device, comprising a receiving hopper with an appliance for adjusting the clear passage of its outlet, with at least a single rod, fitted with guard rings and running concordantly to the longitudinal axis of said hopper, said rod being suspended from coupling rods and carrying a bell adapted to close the outlet of a hopper located above a furnace top, wherein, according to the invention, the appliance for adjusting the cross-sectional area and shape of the receiving hopper outlet is made as sector shields forming a hopper-shaped surface with an annular adjustable gap around the tapered guard ring set on the rod, said sector shields being fixed in guideways and linked mechanically with their longitudinal transfer drives.
The present charging device makes it possible to improve charge distributing at the furnace top by both more regular peripheral distribution and by charging a batch into a preset section of said furnace top; it allows also simplifying the design of said charging device, enhancing the functional reliability of its gears and their longevity and decreasing gas and dust release through said charging device.
It is preferable that the appliance for adjusting the clear passage of the receiving hopper outlet comprise from 2 to 12 sector shields.
The appliance made up of said number of the sector shields is more convenient in terms of their control and features a simpler design.
The bottom edges of said sector shields are advisable to be of such a size as to provide said annular gap around the rod guard ring, the gap being at least 1.5 times less than that between the bottom edge of the receiving hopper outlet and the rod guard rings, but exceeding in size a gap which may cause the hanging of charge in said receiving hopper.
Such a design would obviate the hanging of the charge in the receiving hopper, provide for uniform peripheral distribution of the charge at the furnace top and enhance the reliability of operation of a blast furnace.
It is preferred that the tapered guard ring be made as a distributing bell and be linked mechanically with a gear adapted to transfer it along the rod.
Such an embodiment of the guard ring would provide better control of radial charge distributing at the furnace top without resorting to cumbersome gears to be arranged inside a blast furnace; it allows also simplifying the construction of the charging device and, which is of prime importance, cutting down the overall dimensions of the large bell and its hopper.
The top part of said distributing bell can mount a cylindrical guard ring, said ring being located beneath another guard ring, whose external surface has a configuration of one-sheet hyperboloid of revolution.
This will make it possible to deflect the flow of charge, bringing it closer to the longitudinal axis of the charging device and enhancing thereby the uniformity of its peripheral distribution at the furnace top.
It would be preferable, if the appliance for adjusting the clear passage of the receiving hopper outlet is equipped with a sensor capable of traveling along the coupling rod of the bell rod, being actuated in case the hanging of charge occurs and delivering a signal to the actuating gear of the sector shield transfer drive.
It would avoid the overloading of the receiving hopper, raising (drawing apart) the sector shields with the aid of their drives and eliminating the charge hanging in the receiving hopper; it would also enhance the reliability and longevity of operation of the charging device.
It is sound practice that the bottom edge of the receiving hopper be fitted with projections shaped as isosceles triangles with appropriate lateral sides of said triangles running parallel to the adjoining parts of the side edges of the adjacent sector shields.
Owing to the use of said projections the design of the proposed charging device can be made simpler, the overall dimensions of the sector shields reduced and their transfer drive ratings cut down.
Each of said sector shields can be made as a frame with strips in a wear-resistant material secured thereon.
The strips can be replaced as they wear out, or the strips of appropriate dimensions can be placed with a view to adjusting the annular gap between the rod guard rings and the bottom edges of the sector shields, which would allow taking into account both the charge size and its chemical composition.
It is preferable that each of said sector shield guideways have a narrowed part adjoining the running gear of the appropriate sector shield.
The provision of said guideways would make it possible to avoid the wedging of the sector shields during their travel, enhancing thereby their functional dependability.
It would be favorable if the end portions of said guideways have holes, with a pivot being introduced into each of said holes, said pivot being provided with a detent that is registered in a preset position, shaped as a helix and capable of interacting with the sector shield running gear.
Such a design allows adjusting the extreme positions of the shields and the outlet configuration, providing for more regular peripheral distribution of the charge at the furnace top.